November Bicycles Tests Prototype Aero Wheels w/ Their First Proprietary Design

“Kirkpatrick added that the combination of good rims and good brake pads means you can stay off the brakes longer, which means less dragging, which ultimately means less overall heat generation to begin with.”

Folks with physics degrees, please chime in. I’d say that the overall heat generated has to be the same no matter what rims or pads you use, because what a brake does is convert momentum to heat. Same bike weight, same start speed, same speed reduction = same total heat generated. (Actually bad brakes will have a small advantage, because more time spent braking means more time getting slowed down by air resistance.)

If there is an advantage here, my guess is that with more brake power you spend less time braking, the rim spends less time getting heated, so the heat has less time to transfer throughout the rim where it can do structural damage or blow a tire. The tradeoff is a higher temperature spike in the brake track.

Why the wheel is not confronted to the most aerowheel… the CXR 80!!! Mystery

This is why I will continue to love November as a company. They’re really open about what they do. None of that super secret “this is our new technology with a weird-a** name that we claim makes you X% faster” bullsh*t you get from other companies. I’ll gladly take a massive chunk of the performance and save a similarly sized chunk of cash with their products over something from companies like Zipp because of how they run themselves.

On face value Kirkpatrick’s comment about brakes creating less heat is inaccurate or at best an oversimplification. What he might have meant is that it creates less heat problems ? However, longer braking doesn’t make better braking for a number of reasons.

One of the issues regarding dragging your brakes or longer braking periods is that it gives more time to transfer the heat involved in braking into the rim and pad material rather than dissipate it.

In an ideal world the heat from the braking would be immediately vented away from the braking materials and it would continue to operate at whatever ideal temperature for braking is determined by the relative materials. In the real world longer braking periods allow the heat to be transferred to the materials and this causes brake fade, damage to the surfaces and a rolling drop in performance.

Another variable in the system is how the energy gets transferred in the entire system. Powerful brakes cause heat but also flex in the wheel and frame, therefore some of the energy is split away from the direct kinetic/heat equation. Dragging brakes have a more 1 to 1 correlation of transfer.

The two parts he described would be better labeled as making the materials have a higher heat tolerance and better dissipation of the heat generated ?

Loki –

I think you and I are actually in lock step agreement. If it’s not clear from what was attributed to me (I think it was but I have the bias of knowing what I meant), dragging brakes is the worst thing you can do – it continually heats the pad and rim, and causes pad glazing which turns this into a vicious cycle.

The new SwissStop pads do indeed vent better – you can’t miss the vents. But the way I think about it is this – imagine a cast iron Dutch oven and an aluminum stock pot. They play the role of your brake pads. Your hands play the role of your rims. Heat each pot to the same temperature, turn off the flame, and wait two minutes. Grab the handle and lift the cover on each. The iron cover will burn your hand badly, while the aluminum cover will certainly feel warm, but it probably won’t burn you. That’s similar to the dynamic I’m trying to describe – rapid dissipation of heat, so you aren’t imposing a searing hot pad onto the rim with every squeeze of the brakes. Dragging your brakes is equivalent to never turning off the flame, so that’s obviously just plain bad.

And now a chef will weigh in and tell me how much better and more evenly the dutch oven cooks what’s inside,, and how only a philistine would ever compare the two…

It’s a big challenge to write with enough accuracy to satisfy the technically minded yet still be comprehensible to the majority of the audience, especially when you are space compressed. We might sometimes get that balance wrong, but we’ll never intentionally mislead.

Thanks
Dave

Psi Squared –

The data shown above is actually based on weighted averages, per Tour Magazine’s protocol. The time saved graphic is at 30mph. The watts of drag at different speeds graphic uses a different weighting for each speed (angles widen at slower rider speeds). They aren’t perfect, but they’re very useful – certainly far from meaningless. We’ve spent a ton of time charting apparent wind angles based on various rider speeds and wind speeds, and the huge preponderance of riding time, in competitive situations where wheels such as these would matter, is spent at apparent wind angles of 15 degrees or less. The Tour weighting matched very well with our findings, so in the interest of presenting comprehensible data, we made these graphs. We’ll roll out full spectrum curves for each wheel we tested over the next several days, so you can evaluate them in the conditions you expect to see. Racing crits in the east coast summer would give you a vastly different relevance distribution than riding the Ironman course in Kona, that’s for sure.

Tyler’s done us a huge favor in helping to publicize what we’ve found, but we have posted and will continue to post stacks and stacks of stuff on our site that goes far deeper than what we can do here. For example the blog where the above graphs were first posted has a big discussion of the weighting.

Crosswinds handling is a funny one. I’ve yet to really wrap my head around how to accurately quantify that, and I don’t think the stall break severity is an accurate analog of it – otherwise people riding on some of the fastest deep wheels would be getting thrown sideways whenever their AoA went from 17* to 18*. If the drag vs AoA chart explained it, a HED H3 would be the ultimate crosswind wheel – it’s pretty much a flat line from 0 to 20*. I’ve explained it as well as I can from my significant sailing and sail design background on the blog. Plainly stated, rounder entries are going to give more predictable handling.

The grooves are, as you state, optimized for water and debris clearance, but there is definitely a lot more exposed surface area, and I don’t want to reveal things that aren’t mine to reveal. In any case, SwissStop has tested the Black Prince as developing 170c max heat in a 60kmh to 0 full stop test, compared to 303c max heat with a Yellow King. Distance to stop from 60kmh in wet conditions was reduced from 120m with Yellow Kings to 90m with Black Prince in SwissStop’s testing. Their protocol and testing infrastructure is a lot more elegant than what we’ve used (big reason why we’re having them do our formal testing) but based on our testing, their pads stop better with less heat issues.

This is the ultimate David vs. Goliath story. They have nice technical justifications for their design features on their blog, but it sounds almost too good to be true. 95+% of the aerodynamics of a 404 achieved with a shallower rim depth and an 18 mm wide inside width, too, to achieve that “tubular-like ride quality”.

From what I could see on their website, though, this company has mostly dealt with open-mold components. So after consulting, tool design and cost, resin and layup research and testing, or whatever else they have to do to bring this concept to life, its hard to imagine that they will be able to offer these rims at a price even close to that of their current line-up. If they could, though, it would be the golden bullet. This story will be interesting to follow and Im definitely rooting for them!